The present invention relates to the field of image data display. More specifically, the present invention relates to a system and method for the dynamic display of three-dimensional image data.
Three-dimensional (3D) ultrasound imaging is a technique in which a set of spatially related two dimensional ultrasound slices (tomograms) of a target are collected and mathematically converted to create a virtual Cartesian ultrasound volume. This virtual ultrasound volume facilitates the visualization of non-acquired slices of the target and a variety of rendered surfaces and projections of the target otherwise unobtainable using two-dimensional (2D) ultrasound imaging.
High fidelity 3D ultrasound requires, by definition, a data set in which the spacial relationship between the individual ultrasound slices is precisely known. High fidelity ultrasound is important for the accurate assessment of volumes and the appreciation of target geometry. The conventional method of choice for obtaining the precise spatial relationship between ultrasound slices is to actively constrain the position of each ultrasound slice. This is achieved by controlling the position of the ultrasound probe during generation of the slices by use of a motorized positioning device (mechanical scanning). Examples of 3D ultrasound imaging systems are described in detail in U.S. Pat. No. 5,454,371 (Fenster et al.) and U.S. Pat. No. 5,562,095 (Downey et al.), the contents of each of which are hereby incorporated by reference.
In the three-dimensional ultrasound imaging systems described in the afore-mentioned United States patents, when a succession of two-dimensional images have been captured and digitized, the two-dimensional images are stored as a stack to form an image data array. Before a three-dimensional image of the scanned volume can be created and viewed by a user, the image data array must be reconstructed to form a volumetric image array. This type of reconstruction, in which every pixel in every two-dimensional image slice is converted into an appropriate voxel in an image volume (i.e. volumetric image array) prior to display is known as xe2x80x9cfull volumexe2x80x9d reconstruction. The generation of the complete volume array is somewhat inefficient, i.e. it is a time-consuming intermediate stage. Full volume reconstruction and display of a three-dimensional image using a conventional hardware platform can take upward of one minute and, therefore, has limited application in situations where immediate display of an acquired image is desirable.
In an attempt to overcome the drawbacks associated with full volume reconstruction, the applicants developed a so-called xe2x80x9cfastxe2x80x9d reconstruction process which is described in copending U.S. patent application Ser. No. 08/562,590 (which corresponds to International patent application publication number WO 97/20288), and U.S. provisional patent application serial No. 60/041,345, filed Mar. 21, 1997, the contents of each of which are hereby incorporated by reference.
In fast reconstruction, only the specific image data from the two-dimensional image slices that are actually required to view the user-selected image undergoes reconstruction. In other words, only the image data necessary to view the surface of user-selected image (i.e. as opposed to all of the data representing the entire volume of the target) is used for reconstruction. If, for example, the users wishes to view a particular image of the target volume, the computer uses associated calibration and acquisition parameters of the collected two-dimensional image slices to determine special xe2x80x9clook-upxe2x80x9d tables which speed up the determination of which data points from the two-dimensional image slices are required to be displayed on the monitor. Only the two-dimensional data points necessary to produce the desired image are reconstructed. There is no necessity to construct a full volume image array. Accordingly, this fast reconstruction is more efficient than conventional full volume reconstruction, i.e. it is less time-consuming (less than {fraction (1/2+L )} second). 
Both xe2x80x9cfull volumexe2x80x9d and xe2x80x9cfastxe2x80x9d reconstruction techniques are capable of generating and displaying high quality, single, three-dimensional images of a target, i.e., a temporal xe2x80x9csnap-shotxe2x80x9d of the target. These techniques are particularly useful in displaying images of non-dynamic, effectively stationary targets such as the breast, prostate or liver. However, the display of a single xe2x80x9csnap-shotxe2x80x9d is not optimally effective for imaging a dynamic target such as the heart or lungs.
It is an object of the present invention to provide a system and method for dynamic image display which obviates and mitigates at least one of the disadvantages of the prior art.
Accordingly, in one aspect the present invention provides a system for the dynamic display of three-dimensional (3D) images of a target, comprising:
memory means to store a plurality of time-dependent 3D image data sets;
an address pointer defining an independent address of a location in the memory means of each time-dependent 3D image data set; and
display means utilizing the address pointer successively to retrieve a time-dependent 3D image data set from memory and display a time-dependent 3D image corresponding to the time-dependent 3D image data set for a selected period of time.
In another of its aspects, the present invention provides a system for the dynamic display of three-dimensional (3D) images of a target volume, the system comprising:
scanning means to scan a target volume and generate a succession of digitized two-dimensional (2D) images thereof;
timing means to determine the time interval between generation of the succession of 2D images;
reconstruction means to generate a plurality of time-dependent 3D image data sets of the target volume from the succession of digitized 2D image;
memory means to store the plurality of time-dependent 3D image data sets;
an address pointer defining an independent address of a location in the memory means of each time-dependent 3D image data set; and
display means utilizing the address pointer successively to retrieve a time-dependent 3D image data set from memory and display a time-dependent 3D image corresponding to the time-dependent 3D image data set for a selected period of time.
In yet another of its aspects, the present invention provides a method for the dynamic display of three-dimensional (3D) images of a target, comprising the steps:
(i) storing a plurality of time-dependent 3D image data sets in a memory;
(ii) defining an independent address of a location in the memory means for each time-dependent 3D image data set; and
(iii) retrieving a time-dependent 3D image data set from memory;
(iv) displaying the time-dependent 3D image corresponding to the time-dependent 3D image data set for a selected period of time; and
(v) repeating Steps (iii) and (iv) for each remaining time-dependent 3D image data set.
In yet another of its aspects, the present invention provides a method for the dynamic display of three-dimensional (3D) images of a target volume, the system comprising:
(i) scanning a target volume and generating a succession of digitized two-dimensional (2D) images thereof;
(ii) determining the time interval between generation of the succession of 2D images;
(ii) generating a plurality of time-dependent 3D image data sets of the target volume from the succession of digitized 2D image;
(iii) storing a plurality of time-dependent 3D image data sets in a memory;
(iv) defining an independent address of a location in the memory means for each time-dependent 3D image data set; and
(v) retrieving a time-dependent 3D image data set from memory;
(vi) displaying the time-dependent 3D image corresponding to the time-dependent 3D image data set for a selected period of time; and
(vii) repeating Steps (v) and (vi) for each remaining time-dependent 3D image data set.
The terms xe2x80x9cdynamic image displayxe2x80x9d and xe2x80x9cdynamic display of three-dimensional imagesxe2x80x9d are used interchangeably throughout this specification and are intended to include any method and/or system capable of displaying, in a time-dependent sequential manner, a three dimensional image of a target (e.g., organ, bodily structure, etc.) which is in a state of motion. The effect of this is to enable three dimensional visualization of changes in a target over time. Non-limiting examples of applications of dynamic image display in which the present invention is useful include imaging of a beating heart, assessment the change of a physiological structure in the process of disease progression and the like.